The Port of Halifax stands to lose up to five per cent of its container business as a consortium of five shipping lines cancels its weekly call.

The Green Alliance consortium deploys some of the largest container ships in the world from Southeast Asia. One of its main customers, Canadian Tire, off-loads its goods in Halifax for transport to the rest of Canada.

The group says it's dropping Halifax in September because it needs to improve the route's on-time performance. The other North American stops, including New York and Savannah, remain on the route.

"It does reflect the fact we aren't centred in the most populous part of North America," said Michele Peveril, spokeswoman for the Port of Halifax.

"They've relayed to us that it's not related to Halifax or any type of cost of service issue … In this case it was really more of a scheduling consideration and the need to eliminate some time in the service.

The decision to drop Halifax wasn't easy, said Tim Pajak, spokesman for MOL, an operating partner in the consortium.

"This change was made based entirely on our desire to meet our customers' needs for reliable, on-time delivery," he said.

Peveril said K line, the other operating partner in the consortium, sent the Port of Halifax a letter stating it intends to review the route next year.

Pajak said he wasn't aware of any plan to do so by MOL.

Green Alliance began its service to Halifax in May 2010. At the time it was touted as a big win for the port. It now represents between four and five per cent of the port's annual container volume.

The consortium's decision to leave Halifax is particularly disheartening for the port's Halterm facility, where a multimillion-dollar expansion is underway to deepen a berth and add cranes to handle the largest container ships in the world.

The port is counting on other shipping lines to step in so that Canadian Tire and other companies can still get their products to Halifax.

"We expect that some of the Atlantic Canadian and Ontario cargo — that's what was primarily being handled here on this line — can be carried by other shipping lines that currently call Halifax and call into Asia," said Peveril.

Container traffic at the port improved last year, but it's still less than half of what the port can handle.